With Spanish right-back Antonio Barragán recently becoming the fifth new signing of the summer and three more expected in the near future, Karanka appears to be leaving tactical work until the bulk of his squad can play together on the training pitch.

Karanka looks to get squad in shape

“We are working hard, we have a lot of players who weren’t here last season," Karanka told the club's official website.

“For that reason, it’s difficult to train tactics – we’re thinking more about the physical side.”

Boro's first signing of the summer Viktor Fischer made his long-awaited debut for the club at the Keepmoat Stadium, playing the second 45 minutes as Karanka once again opted to change his entire team at half-time.

€14million man Marten de Roon continued his promising start to life on Teesside while Barragán, Víctor Valdés and Bernardo Espinosa all travelled to Doncaster without featuring on the pitch.

Karanka was pleased with the attitude of these new arrivals, saying they were proof that he has "a really good squad".

"They wanted to come [to Doncaster] with the team because of the atmosphere," he claimed.

Gibson deligted with new arrivals

Young defender Ben Gibson has echoed these views, telling the club's website that he has been impressed with the new faces at the club both on and off the pitch.

“They’re all nice lads who have come in and worked hard,” the 23-year-old said. “We’ve got a very good group of people here."

Gibson was quick to add that "you can't tell too much about people until the going gets tough", but repeated that the players who have arrived at the Riverside are "lovely lads and good footballers more importantly".

Transfer trio hope to join Marbella trip

Middlesbrough are hopeful that deals to bring in Gastón Ramírez, Neven Subotić and Álvaro Negredo will be completed while the players travel to their pre-season training base in Marbella.

Ramírez and Subotić are waiting on work permits before finalising their transfers, while Valencia forward Negredo is reported to be hopeful of joining the club on a season-long loan in the near future.

Boro jet off for Marbella on Monday July 18 with three friendly games arranged, starting with a clash with Real Betis the following evening.